The present invention relates generally to inkjet printheads, and more particularly to inkjet printheads having very high nozzle packing densities.
A conventional inkjet printing system includes a printhead, an ink supply which supplies liquid ink to the printhead, and an electronic controller which controls the printhead. The printhead ejects ink drops through a plurality of orifices or nozzles and toward a print medium, such as a sheet of paper, so as to print onto the print medium. Typically, the orifices are arranged in one or more arrays such that properly sequenced ejection of ink from the orifices causes characters or other images to be printed upon the print medium as the printhead and the print medium are moved relative to each other.
Typically, the printhead ejects the ink drops through the nozzles by rapidly heating a small volume of ink located in vaporization chambers with small electric heaters, such as thin film resisters. Heating the ink causes the ink to vaporize and be ejected from the nozzles. Typically, for one dot of ink, a remote printhead controller typically located as part of the processing electronics of a printer, controls activation of an electrical current from a power supply external to the printhead. The electrical current is passed through a selected thin film resister to heat the ink in a corresponding selected vaporization chamber. The thin film resistors are herein also referred to as firing resistors. A drop generator is herein referred to include a nozzle, a vaporization chamber, and a firing resistor.
The number of nozzles disposed in a given area of the printhead die is referred to as nozzle packing density. Current inkjet printhead technology has allowed the nozzle packing density to reach approximately 20 nozzles per square millimeter (mm2). Nevertheless, there is a desire for much higher nozzle packing densities to accommodate high printing resolutions and enable increased number of drop generators per printhead to also thereby improve printhead drop generation rate.
For reasons stated above and for other reasons presented in greater detail in the Description of the Preferred Embodiments section of the present specification, an inkjet printhead is desired which has a very high nozzle packing density to permit a very high number of drop generators on the inkjet printhead.
One aspect of the present invention provides an inkjet printhead including a substrate having an ink feed slot formed in the substrate. The ink feed slot has a first side and second side along a vertical length of the ink feed slot. A first column of drop generators is formed along the first side of the ink feed slot. A second column of drop generators is formed along the second side of the ink feed slot. Each drop generator in the first and second columns of drop generators includes a nozzle. A nozzle packing density for nozzles in the first and second columns of drop generators including the area of the ink feed slot is at least approximately 100 nozzles per square millimeter (mm2).